Computing devices, such as notebook computers, personal data assistants (“PDAs”), and mobile handsets have user interface devices, which are also known as human interface devices (“HID”). One type of user interface device that has become more common is a capacitive sense interface. This technology is often referred to as capacitive touch-sense technology; however, this term is a misguided term since the user need not actually physically touch the interface to operate the technology. Rather, the user need only bring a conductive object, e.g., a finger, in close proximity to the capacitive sense interface.
Capacitive sense interfaces may assume a variety of shapes and sizes. FIG. 1A illustrates a conventional circular slider interface 105 having a center mechanical button 110. The illustrated circular slider interface 105 includes eight radial capacitance sensors 115 encircling mechanical button 110 and a processing device 120. Processing device 120 monitors capacitive changes in each of capacitance sensors 115 to register user interactions with circular slider interface 105. Circular sliders may be used to convey absolute positional information of a conductive object, such as to emulate a mouse in controlling cursor position on a display, or to emulate a scrolling function of the mouse. Circular sliders may also be used to actuate one or more functions associated with sensing elements of a sensing device.
FIG. 1B illustrates a conventional linear slider interface 130. Linear slider interface 130 includes a surface area on which a conductive object may be used to position a cursor in the x-axis (or alternatively in the y-axis). Linear slider interface 130 may include a one-dimensional array of capacitance sensors 135. When a conductive object makes contact or comes in proximity with a particular portion of linear slider interface 130, the individual capacitance sensors 135 will sense capacitive variations that are translated into an absolute or relative user interaction position. The capacitance variation may be sent as a signal to a coupled processing device (not illustrated) for analysis. For example, by detecting the capacitance variation of each sensor element, the position of the changing capacitance can be pinpointed. In other words, it can be determined which sensor element has detected the presence of the conductive object, and the motion and/or the position of the conductive object over multiple sensor elements can also be determined.
FIG. 1C illustrates a conventional touch pad interface 140. Touch pad interface 140 is often used in notebook computers to emulate the function of a personal computer (“PC”) mouse. A touch pad interface is typically embedded into a PC notebook for built-in portability. Touch pad interface 140 can replicate mouse x/y movement by using two defined axes which contain a collection of sensor elements that detect the position of a conductive object, e.g., a finger. Mouse right/left button clicks can be replicated by two mechanical buttons, located in the vicinity of touch pad interface 140, or by tapping commands on touch pad interface 140 itself. Touch pad interface 140 provides a user interface device for performing such functions as positioning a cursor or selecting an item on a display. Touch pad interface 140 may include multi-dimensional sensor arrays for detecting movement in multiple axes. For example, touch pad interface 140 may be implemented as a two-dimensional array of linear sliders.
Accidental or unintentional user interaction is a concern when using capacitive touch-sense technology because a user need only bring his/her finger proximate to a capacitive touch-sense interface. When a user places his/her finger proximate to a capacitive sense interface, more than one capacitance sensor may sense a capacitive change. Traditional technology attempts to overcome this drawback by treating a capacitance sensor that first senses the capacitive change or that senses a greatest capacitance change as the capacitance sensor that the user likely intended to activate.
However, if the user is not careful with which capacitance sensor he/she activates first or is careless with the exact placement of his/her finger, then an activated capacitance sensor may not coincide with the capacitance sensor that he/she intended to activate. These drawbacks can lead to an unpleasurable and unproductive user experience with conventional capacitive touch-sense technology.